Working tool with replaceable working bit

ABSTRACT

A replaceable wear part for mounting on a leading edge of a working tool, the leading edge and the wear part having co-operative guide formations extending generally perpendicular to the leading edge and which provide a socket and projection type of slidable inter-fit whereby the wear part can be driven by a force extending generally perpendicular to the leading edge in order to take-up a working position in which it is secured against displacement from the working position by frictional interengagement between the guide formations on the wear part and the leading edge, and without need for threaded or other separate removable fasteners.

This invention relates to a working tool with a replaceable working bit,and also to the replaceable working bit per se.

The invention is concerned generally with a working tool, whichnecessarily is provided with one or more working edge or face which isdesigned to work on a particular material, and which therefore isexposed to wearing action over a period of time.

However, the invention has been developed primarily in connection with aworking tool which is capable of working on soil or similar materiale.g. sand, gravel, stone, rubble, and which usually has a working edgeto engage the working material concerned. The working edge will besubject to wear over a greater or lesser period of time, depending uponthe required operation, and the material being handled.

In some blade-type of working tools, it is acceptable to carry outsharpening of the edge as it becomes worm, and this can be done a numberof times (by progressive erosion into the main body of the tool) buteventually the entire tool has to be scrapped. In other working tools,it is known to provide replaceable working edges, which are secured tothe main body of the tool by threaded fasteners e.g. bolts or screws,and which are sacrificial, in the sense that the working edges protectthe main body of the tool from wear (which is the expensive component),and which are replaced when an unacceptable level of wear has occurredin the replaceable part.

In connection with soil working tools for use in agriculture, there aremany examples of working elements or working “bits” which arereplaceably mounted on the main body of the tool concerned e.g. a“point” on the share of a plough, a knife on a plough body, or a tip ofa cultivator tine.

In all of these arrangements, it is usual to mount the working elementin position by means of two separate threaded fasteners. This gives arobust mounting of the elements, and by reason of using two separatefasteners, the element is well able to resist any twisting or turningmoments which may be applied to the element in service, in addition toproviding shear resistance to any direct forces tending to separate theelement from the tool.

Evidently, when it become necessary to replace a worn element, the twofasteners have to be released, and a replacement element then installedin place. If this is carried out “in the field”, this is a timeconsuming and difficult task, especially, as is often the case, thefasteners or nut fixings have become damaged, rusted or otherwise becomedifficult to release. The same will apply in respect of routinemaintenance carried out prior to use. In extreme cases, it is necessaryto use a cutting torch to release the fasteners.

Bearing in mind that a large cultivator might have up to sixty separatecultivator tines (each with its own replaceable tip), it can be a majoroperation to replace a full set of worn tips.

In extreme soil conditions e.g. heavy clay plus flints, a new set ofcultivator tips can become worn within three hours and then needreplacement. A tractor to propel such large cultivators might cost ofthe order of £200,000 (about $315,000), and is therefore an extremelyexpensive piece of capital equipment, and possible “downtime” of theorder of three hours represents a serious under utilisation of such ahigh capital cost item.

With a view to simplify the assembly and dis-assembly of replaceablewearing parts, it is known to provide a mounting arrangement on the mainbody of the tool which only requires a single fastener, but necessarilythis requires the provision of a suitably shaped seating which holds thewearing part captive against rotation about the axis of the singlefastener.

One example of such a known mounting arrangement comprises an assemblyof a replaceable wearing part on a main body of a cultivator tine, inwhich the wearing part has a rectangular body which merges into aV-shaped tip at one end, and on its opposite end it has a narrowprojecting lug. A single fastener is taken through the body and througha mounting hole in the tine, and a shaped socket or receiving recessalso in the tine receives the projecting lug in order to provideresistance to any turning action which may be applied in service to thetip and tending to rotate the tip about the axis of the fastener.

In this known arrangement of replaceable cultivator tip, there is stillthe disadvantage of assembly and dis-assembly of the fastener, but inaddition the projecting lug only forms a narrow prolongation of the mainbody of the tip i.e. the main-body is much wider than the lug, and thelug is therefore the sole means of resisting turning forces applied tothe tip about the axis of the fastener. Therefore, this constructionrelies for its strength on the narrow lug, and on which highlyconcentrated stresses may be generated in service which may result inpremature failure.

The invention therefore seeks to provide a novel arrangement ofreplaceable wear part or bit for mounting on a leading edge of a workingtool, and which can be mounted in a working position on the tool, and besecured against displacement from the working position, without need forthreaded or other separate removable fastener(s).

According to one aspect of the invention there is provided a replaceablewear part for mounting on a leading edge of a working tool, said leadingedge and said wear part having co-operative guide formations extendinggenerally perpendicular to the leading edge and which provide a socketand projection type of slidable interfit whereby the wear part can bedriven by a force extending generally perpendicular to the leading edgein order to take-up a working position in which it is secured againstdisplacement from the working position by frictional interengagementbetween the guide formations on the wear part and the leading edge, andwithout need for threaded or other separate removable fastener.

Therefore, a replaceable wear part according to the invention can bedriven e.g. by a hammer to take-up its working position, and theco-operative guide formations allow the wear part to slide in adirection generally perpendicular to the leading edge. The guideformations are arranged to exert a wedging action on the wear part, sothat the greater the distance travelled, the stronger will be thefrictional engagement forces acting between the guide formations.

In a preferred arrangement, the guide formations in the leading edge ofthe tool form a socket whose width reduces with distance perpendicularlyinwardly of the leading edge, so that a progressively increasing wedgingforce can act on a wear part as it is driven internally of the socket.

The socket may be defined between a pair of opposed side walls which areconvergent or taper, and the wear part has opposed external side faceswhich are also convergent or taper, but to a greater extent than thetapering of the side walls of the socket, so that an increasing wedgingforce is generated therebetween as the wear part is driven to itsworking position, whereby also the frictional resistance againstpossible displacement increases progressively.

The co-operative guide formations preferably also have aninterengagement which opposes any relative rotation of the wear partabout its longitudinal axis.

The walls or faces defining the guide formations may be of matchingV-shape in cross section, though other cross sectional shapes may beprovided, such as to oppose rotation of the wear part about itslongitudinal axis, and relative to the leading edge.

Preferably, the invention comprises an assembly of the replaceable wearpart and the working tool in combination.

The wear part may comprise a working bit to be mounted on a transverselyextending leading edge of an agricultural tool, such as a “point”(preferably a reversible point), a ploughshare, or a cultivator tine.However, the invention may be applied to other types of working toolthan agricultural tools e.g. an excavator bucket (front or rearmounted), or a loading shovel, each having a leading edge provided withexcavator teeth mounted thereon along the length of the leading edge, inwhich each excavator tooth comprises a replaceable wear part accordingto the invention.

Preferred embodiments of the invention will now be described in detail,by way of example only, with reference to the accompanying drawings, inwhich:

FIG. 1 is a plan view of a first embodiment of the invention in the formof a ploughshare in assembly with a wear replaceable part, or “bit”which is force-fitted in order to take-up a mounting position in theleading edge of the share;

FIG. 2 is a side view of the assembly;

FIG. 3 is a section taken on the section line A—A in FIG. 1, and showingthe engagement between the external side faces of a mounting portion ofthe wear part, and the side profiles of the socket defined in theleading edge of the share;

FIG. 4 is a plan view of a second embodiment of the invention in theform of a replaceable tine point tip for mounting on the end of a tine,shown in exploded, unassembled form;

FIG. 5 is a side view of the tine point tip shown in FIG. 4;

FIG. 6 is a plan view of another example of tine point tip after it hasbeen driven to a working position mounted on the end of a cultivatortine;

FIG. 7 is a side view corresponding to FIG. 6;

FIG. 8 is a cross section taken on the section line A—A in FIG. 6, andshowing the slidable interengagement between the external side faces ofa mounting portion of the tine point tip, and the side profiles of thesocket provided in the leading end of the cultivator tine which receivesthe mounting portion;

FIG. 9 is a plan view of the leading end of a cultivator tine, showingthe recess or socket which receives the mounting portion of the tinepoint tip (of FIG. 4 or 6);

FIG. 10 is an end view showing the side profiles of the socket;

FIG. 11 is a plan view of a third embodiment of the invention, showing areplaceable wear bit mounted (by force-fit) at the leading end of aninclined leading edge of a reversible point;

FIG. 12 is a plan view of a fourth embodiment of the invention; and,

FIG. 13 is a side view of the fourth embodiment.

Referring now to the drawings, there will be described preferredembodiments of replaceable working part or bit according to theinvention, and adapted for mounting on a working tool having one or moreworking edge or face which is designed to work on a particular material,and which is exposed to wearing action over a period of time.

The preferred embodiments which will be described comprise soil workingtools for use in agriculture, but it should be understood that theinvention has wider application, and can be applied to replaceableworking bits per se, and to other types and combinations of working toolrequiring replaceable working bits to be mounted thereon, and withoutneed for threaded or other fasteners to assemble and disassemble thecombination.

Referring first to FIGS. 1 to 3, a first embodiment of the invention isillustrated, and which comprises the combination of a plough share (anda replaceable wear part or “bit”), designated generally by reference 10,and which has usual mounting holes 11 along its lower edge, whereby theshare 10 can be mounted on a plough, and when mounted in position, it isthe transversely extending leading end or edge 12 of the share 10 whichis the frontal part of the share and which first engages the soil duringforward movement of the plough body. A replaceable wear part or bit,designated generally by reference 13, is mounted (by force-fit) in theleading end 12 of the share 10, so that it takes up a working position,after being driven by a force extending generally perpendicular to theleading edge 12 e.g. by a hammer. In the working position, the wear part13 is secured against displacement from the working position byfrictional inter-engagement between co-operative guide formations on thewear bit 13 and a suitable receiving formation provided in the leadingedge, and without need for threaded or other separate removablefasteners.

In the illustrated embodiment, a receiving socket 14 is formed in theleading end region 15 of the share 10, and socket 14 is defined by apair of opposed profiled side edges 16 (see FIG. 3) which converge ortaper, as can be seen in FIG. 1, whereby a progressively increasingwedging action is applied to a projecting mounting portion 17 of thewear bit 13.

The mounting portion 17 has opposed external side edges 18, which alsoare convergent, but to a lesser extent than the convergence of the sideedges 16 of the socket 14, whereby progressive axial movement of themounting portion 17 inwardly of the socket 14 results in a progressivelyincreasing wedging action, and frictional force acting between theco-operative guide formations (the internal side faces 16 of socket 14and the external sides 18 of mounting portion 17).

The wear bit 13 is made of suitable hard wearing material e.g. forgedmetal, and clearly the greater part of any wearing action applied to thecombination of the share 10 and bit 13 will be borne by the bit 13,since it is the first part of the combination to engage unworked soil.The working forces applied to the bit 13 will generally tend to forcethe mounting portion 17 still further into the socket 14, and thereforeduring normal operation, there is no risk of the bit 13 becomingdislodged from its mounting position. Evidently, any forces applied tothe bit 13 other than axially extending forces, may apply a turningmoment to the bit 13, but any rotation of the bit 13 in the socket 14will be resisted by the way in which the guide formations inter-engage.Furthermore, any possible tendency of the bit 13 to rotate about itsgeneral longitudinal axis 19 will be borne by the co-operativeinter-engagement between each external side 18 of mounting portion 17and the corresponding internal side edges 16. As can be seen clearlyfrom FIG. 3, each of the co-operative guide formations is V-shaped, andclearly the inter-engagement will be such as to strongly oppose anyrotational forces applied to the wear bit 13, about the longitudinalaxis 19.

In use of the combination of the share 10 and the wear bit 13, the share10 will be exposed to wearing action as it moves through the soil, butthe major part of any wearing forces will be borne by the wear bit 13,and which will be made of suitable wear resistant material, and this incombination with the robust but simple mode of mounting in position,will mean that the wear bit is exposed to the major wearing action,thereby prolonging the effective life of the share 10.

The wear bit 13 can be easily mounted in position, by simple applicationof a driving force e.g. by a hammer, which force fits the mountingportion 17 into the socket 14. However, the wear bit 13 will be exposedto wearing action over a period of time, and when an unacceptable levelof wear has occurred, it is a simple matter to dis-assemble thecombination, by insertion of a wedging tool (not shown) between theinboard end 20 of the mounting portion 17 and the inner end 21 of thesocket 14. Therefore, replacement of a worn bit 13 can take placeeasily, either during routine maintenance, or in the field whennecessary, and without need to release threaded fasteners as used inknown arrangements.

Evidently, the combination shown in FIGS. 1 to 3, is a socket andprojection type of inter-fit, and in which the projection is provided onthe wear part 13 and the socket is provided in the leading end of theshare 10. However, these arrangements could be reversed, whereby amounting projection extends from the leading end 12 of the share 10, anda wear part with a receiving socket or recess can be driven onto theprojection. A similar wedging action, and also resistance to rotationwill be provided by the co-operative engagement between the respectiveguide formations.

Referring now to FIGS. 4 and 5, there is a shown a second embodiment ofthe invention, applied to a cultivator tine (see also FIGS. 9 and 10),and replaceable tine point tip. The tip is shown in FIG. 4, anddesignated generally by reference 22, and having a rectangular main body23, and which is provided with a V-shaped tip 24 at one end, and arearwardly projecting mounting portion 25 at its opposite end. Themounting portion 25 performs a similar function to mounting portion 17of wear bit 13 in the first embodiment, and is driven into frictionalengagement in a socket or recess 26 formed in a lower mounting end 27 ofa cultivator tine (shown in exploded, unassembled form). Theinter-engagement between the mounting portion 25 and recess 26 isgenerally the same as in the first embodiment, and after driving of thetine point tip 22 (which is a further example of a replaceable wear partor bit) to a working position in the recess 26, the frictionalinter-engagement between the co-operative guide formations is sufficientto hold the tip 22 in the working position. Also, as in the previousembodiment, there is resistance to any turning moments which may beapplied in service to the tip 22, by the co-operative engagement betweenthe guide formations.

An alternative type of wear part 22 a is shown in FIGS. 6 to 8, inassembly with a cultivator tine or other agricultural tool 27 a.

Referring to FIG. 11, a third embodiment of replaceable wear part or bitis shown, for assembly with a reversible point, designated generally byreference 30. The point 30 has an inclined leading edge 31, and areplaceable wear bit 32 is driven e.g. by a hammer, to take up theworking position shown in FIG. 11, within a recess or socket 33 providedin the leading end region 34 of the point 30. Again, co-operative guideformations are provided on the opposed inner side edges of the recess33, and the opposed external sides of the wear bit 32, which providerequired frictional engagement to hold the wear part 32 in the workingposition, after it has been driven to the working position by axialsliding movement. There is also resistance against any turning momentsapplied to the wear bit 32 in service.

It should be noted particularly from FIG. 11 that the wear bit 32 islocated at or close to the leading edge region 31 a of the inclinedleading edge 31 of the point 30. Therefore, in practice, virgin orunworked soil will be engaged first by the leading end 32 a of the wearbit 32, and since the wear bit 32 will be made of a material which isstrongly resistant to abrasive action, it can have a long service life,and as it projects forwardly of the leading edge 31, even by a smallamount, it will be exposed to the greatest wearing action of theunworked soil, and which loosens the soil, and which then undergoesfurther working action by continued forward movement of the leading edge31.

The wear bit 32 is driven to the working position in the socket, andonce an unacceptable level of wear has arisen, the wear bit 32 can beremoved by driving a wedging tool (not shown) between the inner ends ofthe wear bit 32 and the recess 33 in which it is mounted.

The embodiments shown in the drawings are examples of the inventionapplied to agricultural tools, and replaceable wear parts or bits foruse with such tools. However, the invention is applicable to otherexamples of working tools having a leading edge or face, exposed to awearing action, such as the leading edge of an excavator bucket orshovel.

Usually, excavator buckets have digging teeth mounted along the leadingedge, and at present the mounting of these teeth is by means of threadedfasteners, rivets and other similar fastenings. However, it should beunderstood that the concept of replaceable wear bits, without use ofthreaded fasteners, can be applied to digging teeth provided onexcavator buckets and the like.

A fourth embodiment of the invention is illustrated in FIGS. 12 and 13,and comprises a holder 40, and a point 41 having a slidable inter-fitwith the holder 40, by way of co-operative guide formations, and whichallow the point 41 to be driven by a force extending generallyperpendicular to the leading edge in order to take-up a working positionin which it is secured against displacement from the working position byfrictional interengagement between the guide formations, and withoutneed for threaded or other separate removable fasteners.

The fourth embodiment shown in FIGS. 12 and 13 is generally similar tothe other embodiments. Essentially, it comprises a holder of the typeshown in FIG. 9, and a point of the type shown in FIG. 4. The holder 40is mounted on a tine 42, and the holder 40 is in two parts, comprising amain part 43 forming a central holder, and to which the point 41 isdetachably secured, and a rear/upper holder path 44 which is secured tothe tine 42 via a single bolt 45. However, to prevent the wear holderpart 44 from rotating about the volt 45, and therefore wobbling inservice there is a sloping tongue 46 fitting into a corresponding notchor groove 47 in the main holder part 40.

What is claimed is:
 1. A replaceable wear part for mounting on a leadingedge of a working tool, said leading edge and said wear part havingco-operative guide formations extending generally perpendicular to theleading edge and which provide a socket and projection type of slidableinter-fit whereby the wear part can be driven by a force extendinggenerally perpendicular to the leading edge in order to take-up aworking position in which it is secured against the displacement fromthe working position by frictional inter-engagement between the guideformations on the wear part and the leading edge, and without need forthreaded or other separate removable fasteners, said co-operative guideformations allowing the wear part to slide in a direction generallyperpendicular to the leading edge and providing a wedge-typeinter-engagement between the guide formations such that the greater thedistance travelled, the stronger will be the frictional engagementforces acting between the guide formations: characterized in that theguide formations are defined by walls or faces which are matchingV-shape in cross section to oppose relative rotation of the wear partabout its longitudinal axis, and wherein the socket is defined between apair of opposed side walls which are convergent or taper, and the wearpart has opposed external side faces which are also convergent or taper,but to a lesser extent than the tapering of the side walls of thesocket, so that an increasing wedging force is generated therebetween asthe wear part is driven to its working position, whereby also thefrictional resistance against possible displacement increasesprogressively.
 2. A wear part according to claim 1, and adapted to bemounted on a transversely extending leading edge of an agriculturaltool, selected from a point, a ploughshare, a cultivator tine, or aholding portion of an agricultural tool.
 3. A wear part according toclaim 2, in which the guide formations of the wear part are v-shaped inprofile and are provided on opposed edges of a projecting mountingportion of the wear part.
 4. A wear part according to claim 1, andcomprising a main holder which is detachably securable to a tine, and towhich point is detachably secured, and in which the holder comprises twoparts, namely a main holder part and a rear/upper holder part which canbe fastened to the tine via a single fastener, and which has a tongueand groove type of interfit with the main holder part to preventrotation about the fastener, said rear/upper holding part also servingto act as a wear protecting plate for the tine.
 5. A replaceable wearpart for mounting on a leading edge of a working tool, said leading edgeand said wear part having co-operative guide formations extendinggenerally perpendicular to the leading edge and which provide a socketand projection type of slidable inter-fit whereby the wear part can bedriven by a force extending generally perpendicular to the leading edgein order to take-up a working position in which it is secured againstthe displacement from the working position by frictionalinter-engagement between the guide formations on the wear part and theleading edge, and without need for threaded or other separate removablefasteners, said co-operative guide formations allowing the wear part toslide in a direction generally perpendicular to the leading edge andproviding a wedge-type inter-engagement between the guide formationssuch that the greater the distance travelled, the stronger will be thefrictional engagement forces acting between the guide formations:characterized in that the guide formations are defined by walls or faceswhich are matching V-shape in cross section to oppose relative rotationof the wear part about its longitudinal axis, wherein the socket isdefined between a pair of opposed side walls which are convergent ortaper, and the wear part has opposed external side faces which are alsoconvergent or taper, but to a greater extent than the tapering of theside walls of the socket, so that an increasing wedging force isgenerated therebetween as the wear part is driven to its workingposition, whereby also the frictional resistance against possibledisplacement increases progressively.
 6. A wear part according to claim5, and adapted to be mounted on a transversely extending leading edge ofan agricultural tool, selected from a point, a ploughshare, a cultivatortine, or a holding portion of an agricultural tool.
 7. A wear partaccording to claim 5, and comprising a main holder which is detachablysecurable to a tine, and to which point is detachably secured, and inwhich the holder comprises two parts, namely a main holder part and arear/upper holder part which can be fastened to the tine via a singlefastener, and which has a tongue and groove type of interfit with themain holder part to prevent rotation about the fastener, said rear/upperholding part also serving to act as a wear protecting plate for thetine.
 8. A replaceable wear part according to claim 5, in which theguide formations of the wear part are v-shaped in profile and areprovided on opposed edges of a projecting mounting portion of the wearpart.
 9. A replaceable wear part for mounting on a leading edge of aworking tool, said leading edge and said wear part having co-operativeguide formations extending generally perpendicular to the leading edgeand which provide a socket and projection type of slidable inter-fitwhereby the wear part can be driven by a force extending generallyperpendicular to the leading edge in order to take-up a working positionin which it is secured against the displacement from the workingposition by frictional inter-engagement between the guide formations onthe wear part and the leading edge, and without need for threaded orother separate removable fasteners, said co-operative guide formationsallowing the wear part to slide in a direction generally perpendicularto the leading edge and providing a wedge-type inter-engagement betweenthe guide formations such that the greater the distance travelled, thestronger will be the frictional engagement forces acting between theguide formations: characterized in that the guide formations are definedby walls or faces which are matching V-shape in cross section to opposerelative rotation of the wear part about its longitudinal axis, andcomprising a main holder which is detachably securable to a tine, and towhich point is detachably secured, and in which the holder comprises twoparts, namely a main holder part and a rear/upper holder part which canbe fastened to the tine via a single fastener, and which has a tongueand groove type of interfit with the main holder part to preventrotation about the fastener, said rear/upper holding part also servingto act as a wear protecting plate for the tine.
 10. A replaceable wearpart according to claim 9, and adapted to be mounted on a transverselyextending leading edge of an agricultural tool, selected from a point, aploughshare, a cultivator tine, or a holding portion of an agriculturaltool.
 11. A replaceable wear part according to claim 9, in which theguide formations of the wear part are v-shaped in profile and areprovided on opposed edges of a projecting mounting portion of the wearpart.